In an impassioned speech, he said there was dysfunction in the mortgage market that he thought had cut lending by up to $500 billion a year, boxing out many of the Americans who would benefit the most.

His comments were based on a March 31 report from JPMorgan's fixed-income strategy team saying "under an early 2000s lending regime, another $500bn of new purchase loans could have been extended in 2016."

"If that number is right, shame on us" for not doing something about it, Dimon said.

A primary culprit, in his eyes, has been government regulation in reaction to the financial crisis.

Dimon's message Thursday echoes his letter to investors released in early April. In the letter, Dimon described homeownership as the "embodiment of the American Dream," and he lamented a slow housing recovery, which he blames in part on mortgage credit restrictions.

He acknowledged that after the financial crisis his firm "needed to create a safer and better-functioning mortgage industry," but he said the response was excessive and created new problems.

Dimon described the complex web of government oversight that dampened banks' willingness to lend:

"Seven major federal regulators and a long list of state and local regulators have overlapping jurisdiction on mortgage laws and wrote a plethora of new rules and regulations appropriately focused on educating and protecting customers. While some of the rules are beneficial, many were hastily developed and layered upon existing rules without coordination or calibration as to the potential effects.

"The result is a complex, highly risky and unpredictable operating environment that exposes lenders and servicers to disproportionate legal liability and materially increases operational risks and costs."

The result, Dimon said, has been more expensive mortgages for consumers and less access to people without a sterling credit history.

He cited the following charts in his shareholder letter as evidence that lending had dried up for borrowers with lower credit scores:

JPMorgan

JPMorgan

And in a not-so-subtle jab at pro-regulation pushers, Dimon notes that the people they're trying to protect have lost the most from the industry's heightened governmental scrutiny. He wrote:

"It's noteworthy that those who lost access to mortgage credit are the very ones who so many people profess to want to help - e.g., lower income buyers, first-time homebuyers, the self-employed and individuals with prior defaults who deserve another chance."